<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>并集选择器(union selector)</title>
  <!-- 
    CSS的并集选择器（union selector）用于选择满足任一条件的元素。
   -->
   <style>
    .union-selector, p, h3 {
      color: red;
    }
   </style>
</head>
<body>

  <div class="union-selector">union-selector</div>
  <p>CSS的并集选择器（union selector）用于选择满足任一条件的元素。</p>
  <h3>my name h3</h3>
  
</body>
</html>